Protective device for electrical apparatus



w. F. GAKLE ET AL 1,961,608

PROTECTIVE DEVICE FOR ELECTRICAL APPARATUS June 5, 1934.

Filed May 9. 1952 %n% fi wfiam ATTORNEY.

Patented June 5, 1934 UNITED STATES PATENT OFFICE PROTECTIVE DEVICE FOR ELECTRICAL APPARATUS poration of Michigan Application May 9, 1932, Serial No. 610,090

4 Claims.

One of the prime Objects of the invention is to design a protective device for protecting electrical apparatus from insulation failure, caused by abnormal potentials or surges imposed by various classes of lightning and high voltages disturbances, and to take off safely to ground the peak voltages which may arise during surges or other transient phenomena.

Another object is to provide a simple and practical protective device, which includes the combination of a lightning arrester, a transform-' er terminal, and a transformer bushing, so combined and coordinated, that it will be elficient in operation and economical to construct. With the above and other objects in view, the present invention consists in the combination and arrangement of parts, hereinafter more fully described, illustrated in the accompanying drawing, and particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, and proportions, without departing from the spirit, or sacrificing any of the advantages of the invention.

In the drawing- Fig. 1 is a part sectional side view of our protective device.

Fig. 2 is a top plan view. Fig. 3 is a fragmentary view of the bushing. Fig. 4 is a fragmentary sideview of a transformer case showing the'protective device assembled thereon.

In general practice the elements referred to in thepreamble to thisspecification were separate and individual, and when installed were placed as far apart as was convenient, one object being to place the arrester far out on the arm, and minimize the hazard or possibility of the linemen coming in contact therewith. The separation of the arrester, the transformer terminal,

and bushingdnserted factors detrimental to the proper functioning of, the arrester, as it is well known that the arrester should be as close as possible to the apparatus being protected, but because of the possibility of endangering the lineman, these elements were separate units, and the practical installation would not permit of the ideal installation, further, because of the fact that the arrester functions in draining the ab normal potentials so that they will not be harmful to the apparatus, the protection must of necessity be on the side opposite the source of the abnormal condition; placed inside the case of a transformer protects only that part beyond its electrical connection,

5 and does not protect the part between it and the consequently, an arrester source of the abnormal voltage, and we have found that the most effective and strategic position for the arrester is the transformer bushing itself; this eliminates any hazard for the lineman, provides for more eflicient functioning, and the cost of manufacture and installation is me.- terially reduced.

Referring now more specifically to the drawing in which we have shown the preferred embodiment of our invention, the numeral 6 indicates a case containing a transformer (not shown), and which is adapted to be submerged in oil or other suitable fluid insulating material.

A pocket '7 is formed in the case near the top, and a lead opening (not shown) is provided in the bottom wall thereof, and is adapted to .accommodate the reduced neck portion 8 of a preferably cylindrical bushingmember 9 which is secured thereto, said neckprojecting at an angle from the main body. The lower end of the bushmg is formed with an offset section 10, and a cored passage 11 leads through the bushing and accommodates a line lead 12 as hereinafter more fully described.

The lower end of the bushing is countersunk as at 13 and is adapted to accommodate the shouldered end 14 of a standard lightning arrester 15 which is secured thereto by use of a suitable cement (not shown), the offset section 10 of the bushing projecting beyond the side wall of the arrester to expose the cored passage 11 which accommodates the lead 12. A resilient, preferably cork, gasket 16 is provided on the neck of the bushing and is adapted, when the device is assembled, to be interposed between the 9 main body of the bushing and the case, said gasket forming a weatherproof, tight connection for the lead opening. Pockets 17 areprovided in the bushing in spaced apart relation, and are adapted to accommodate nuts 18 which are threaded on thebolts 19, said bolts extending through the bushing and serve to secure it in position on the case.

A centrally disposed opening 20 is provided in the upper end of the arrester, and a terminal 21 s fitted therein and engages a conducting disk 22, said disk being held in position by means of -a flange 23in. the usual manner, this disk 22 forming a closure for the active element of the arrester 24 which are packed in the arrester casing in contact with said disk. I

These active elements can be carborundum or the like, as carborundum offers low resistance to high potentials, but high resistance to heavy currents, and when a lightning discharge flashes over an arrester, the discharge flows through the ground conductor 25 and automatically grounds the power line, and the carborundum stops the flow of heavy current from the power line alter the lightning discharge is over.

The lead 12 passes into the bushing 9 through the passage 11, the section 12A being stripped, and a screw 26 anchors it to the terminal 21; thence the lead extends up through the neck 8 and is connected to the transformer in the usual manner, the passage 11 being sealed by means of a suitable sealing material.

By the combination and coordination of the parts above described, it is obvious that the line and electrical apparatus are provided with a protective system, which-will function in an eiiicient and reliable manner to drain abnormal potentials and fully protect the apparatus to which it is connected.

What we claim is:,

electrical apparatus, having an opening in its casing, a cored bushing mounted therein and secured to said casing, a lightning arrester secured to said bushing and having a lead to ground, a terminal mounted in said arrester, an open oitset section formed integral with the bushing and a said section and being connected to said terminal and leading through said cored passage to said electrical apparatus.

2. In an encased electrical apparatus having a lead opening in its casing, a cored bushing mounted in said opening, means for securing said bushing in position, a lightning arrester secured line lead accommodated by to said bushing and having a lead to ground, an open offset section formed integral with the bushing and overhanging said lightning arrester, and a line lead leading through said open oflset section and connected to said arrester and to the electrical apparatus respectively.

3. In an electrical apparatus having a line lead connected thereto, a countersunk bushing connected to said apparatus and formed with a reduced .neck, an ofiset section formed integral with the main body, and a passage extending through said section and through said neck, a lightning arrester secured to the bushing and having a shouldered upper end adapted to fit the countersunk end of said bushing, and a terminal mounted in and connected to said arrester and to which a stripped section of the lead line is connected. I v

4. In an encased electrical apparatus having a lead line opening in its casing, a countersunk bushing connected thereto and formed with a reduced neck portion projecting into said opening, an offset section formed on the bushing, a lightning arrester connected to said bushing and formed with a shouldered upper end adapted to fit the countersunk end of the bushing, a terminal mounted in and connected to the upper end of said arrester, an open passage in said oflset section and bushing, and a lead line connected to said terminal and to the electrical apparatus respectively.

WENDOLYN F. GAKLE. HENRY F. KOLLINGER. LEROY F. GOSS. 

